# Projection Vectors Problem

1. Feb 25, 2013

### anonymoususer

1. The problem statement, all variables and given/known data
The angle between two vectors a and b is ∅, where ∅≠90°. Under what conditions will |Projab|2 + |Projba|2 = 1?

2. Relevant equations
|Pab|= |$\vec{a}$$\bullet$$\vec{b}$|/|$\vec{b}$|

|Pba|= |$\vec{a}$$\bullet$$\vec{b}$|/|$\vec{a}$|

3. The attempt at a solution
I know that |Pab|=|Pba| when |$\vec{a}$|=|$\vec{b}$|

I'm not sure where I go from there.

Any help is appreciated, thanks.

2. Feb 25, 2013

### Dick

Looks to me like they just want you to derive an express for cos(∅) in terms of |a| and |b|.

3. Feb 25, 2013

### anonymoususer

I think it's a little more complex than that. I am a little confused on what the question is asking though.

4. Feb 25, 2013

### Dick

I worked through it and that's the only thing I can figure they could be asking.